耦合电容的作用是什么？
参考答案：
通高频，阻工频
To be ______ changing times you cannot have your body in the 21st century and your head back in the past.
A．in step with
B．in front of
C．together with
D．apart from
天车上采用（）滑轮组
A.单联
B.双联
